Self-cleaning magnetic switch



July 26, 1966 s. WINTRISS 3,263,044

SELF-CLEANING MAGNETIC SWITCH Filed March 26. 1965 INVENTOR BY GEORGEWINTRISS swim-km ATTORNEYS.

United States Patent 3,263,044 SELF-CLEANING MAGNETIC SWITCH GeorgeWintriss, Carversville, Fa, assignor to Industrionics Controls, Inc.,New York, N.Y., a-corporation of New York Filed Mar. 26, 1965, Ser. No.442,887 15 Claims. (Cl. 20087) This invention relates to electricswitches and more especially to improvements in magnetic switches.

It is an object of this invention to provide a magnetic switch having amovable contact formed so that there is a self-cleaning action at thepoints of contact.

It is another object of this invention to provide improved magneticswitches operating with a snap action that has no pre-travel.

Some other features of the invention relate to a versatile combinationof fixed contacts and a movable contact, utilizing at least two magnets,to provide a selfcleaning magnetic switch which may function as a singlepole-double throw switch, a momentary open switch, or a momentary breakswitch, dependent upon the electrical connections made to two of threefixed contacts in the switch mechanism.

Other objects, features and advantages of the invention will appear orbe pointed out as the description proceeds.

In the drawings, forming a part hereof, in which like referencecharacters indicate corresponding parts in all the views:

FIGURE 1 is a perspective view of an electrical switch made inaccordance with this invention enclosed in the switch housing;

FIGURE 2 is a perspective view of the switch shown in FIGURE 1 with thetwo halves of the housing separated whereby the switch mechanism isshown;

FIGURE 3 is a sectional view taken on lines 3-3 of FIGURE 1; I

FIGURE 4 is a diagrammatic sectional view taken along lines 44 of FIGURE1; and

FIGURE 5 is a diagrammatic view showing a modified form of the switchwhich may be enclosed in a housing such as that shown in FIGURE 1.

FIGURES l, 2 and 3 show a switch 20 composed of a housing having a lowerportion 21 and an upper portion 22. The housing has an upper side 23,and a lower side 24. The upper portion 22 and the lower portion 21 ofhousing encloses a chamber for a switch mechanism composed of threesubstantially parallel contact bars 34, 38 and 40 connected to the sidewalls, and a round movable contact bar 35. Plunger 32 extends into theswitch chamber.

The switch shown is a single pole, double throw switch. Contact bar 34is electrically connected to an external wire 28. Contact bar 34 whichis connected to the lower portion 21 is a permanent magnet whichattracts the round movable contact bar 35 and acts as the single pole ofthe switch. Round contact bar 35 is made of a para-magnetic material andhas a necked portion 36 in contact with bar 34. The other end of thecontact bar 35 is normally in contact with the contact bar 40 which isalso a permanent magnet. The contact bar 40 is connected to the upperportion 22 and is in electrical contact with an external wire 29. In theswitch mechanisms normally closed position, an electric circuit isformed between contact 34, contact bar 35, and contact 40.

The inner mating faces 25 and 26, respectively, of the upper and lowerportions of the switch housing contain an annular opening 43, one-halfof which is illustrated in FIGURE 2, to provide space for a plunger 32which extends outwardly from the front faces 30 and 31 of the housing.Plunger 32 extends into the switch 'ice mechanism, terminating in anannular lip 33 which is normally in contact with a movable contact bar35 when the bar 35 touches a contact bar 40.

When the plunger 32 is resting in contact with the round contact bar 35and the contact bar is against the magnetic contacts 34 and 40, theswitch is in its normal closed circuit position.

When pressure is applied to the plunger 32, the force against the roundcontact bar 35 increases until it is sufficient to overcome theattraction of the magnetic contact 49 for the round bar 35. The roundbar 35 then moves away from the magnetic contact 40 with a snap actionwhich results from the rapid decrease in the magnetic attraction as theair gap between the magnetic contact 40 and the round bar 35 increases.This produces the snap action. The application of pressure on plunger 32(in contact with bar 35) causes breaking of the contact between magneticcontact 40 and the round contact bar 35 without any pre-travel of theplunger 32.

When the plunger 32 has been depressed and sufficient pressure appliedto break the contact between the round contact bar 35 and the contact40, the round contact bar 35 pivots about the contact 34 as a fulcrumand is thrust into contact with the electrical contact 38. Theelectrical contact 38 is not a magnet. It is connected to the housingportion 21 and is in electrical contact with the external wire 27.

The movement of the round bar 35 into contact with the contact 38 closesan electrical circuit between the contacts 38 and 34 through the roundbar 35. This circuit continues closed so long as pressure is appliedupon the plunger 32. When pressure on the plunger 32 is released, theround contact bar 35 snaps back into contact with the magnetic contact40. This movement is caused by the magnetic attraction of the contact 40for the round bar 35.

FIGURE 4 illustrates the electrical connections of the contacts to theexternal wires. Contact 40 is connected with the external wire 29through a terminal 41. Contact 38 is connected to an external wire 27through a terminal 42. Contact 34 which is not illustrated in FIG- URE 4is connected to the external wire 28 through a terminal in a mannersimilar to the connections between the contact 38 and the wire 27.

It is a particular advantage of the switch mechanism of this inventionthat when the round movable bar 35 is moved under pressure of plunger 32out of contact with magnetic contact 40, there is some rotationalmovement of the round bar 35 about its longitudinal axis. There issimilar rotational movement of said bar 35 when it moves away fromcontact 38 and returns to the closed-circuit position in contact withthe magnetic contact 40. This rotational movement of the round contactbar 35 causes contact with the permanent contact 34 to be made atdifferent points around the periphery of the necked portion 36 of thebar 35. Similarly, the peripheral point of contact of the other end ofthe bar 35 wilh the contacts 40 and 38, respectively, are changed witheach movement of the switch. This imparts a wiping and self-cleaningaction to the contacts at the points where arcing may occur.

To accentuate the rotational movement of the round movable bar 35, it ispreferred that the pressure applied by the plunger 32 to the bar 35,should be applied against the bar 35 in a non-radial direction, therebycreating a moment about the longitudinal axis of the bar 35.

Although the switch mechanism has been described in connection with asingle pole, double throw switch, it is apparent that relatively minormodifications resu't in the same mechanism being useful as a momentarycontact switch, or a momentary break switch.

A momentary contact switch results when the permanent magnet 40 is notan electrical contact so that it is not part of an electric circuit. Thes itch in the normal position having the movable bar 35 contacting thepermanent magnet 34 and the permanent magnet 40 is in an open circuitposition. Movement of the plunger 32 will cause the round movable bar 35to break away from the magnet 40 and touch the electric contact 38thereby forming a closed circuit between the contacts 34 and 33 throughthe movable contact 35. This circuit will remain closed so long aspressure is maintained on the plunger 32. When pressure is released, thecircuit is immediately broken by the attraction of the permanent magnetfor the movable contact 35 and the switch returns to the normally openposition.

The switch operates as a momentary break switch when the bar 38 is notan electrical contact. It functions only as an abutment. The switch isnormally closed forming an electric circuit between the contacts 34 and40 through the movable bar 35. Application of pressure by plunger 32breaks the circuit by moving the bar 35 against the abutment 38.

FIGURE shows a modification of the invention in which the threestationary electrical contacts 101, 102 and 103 are each permanentmagnets. A round movable contact bar 104 has a neck portion 105 at oneend adjacent the contact 103 and another neck portion 106 at the otherend adjacent and between the contacts 101 and 102. The neck portion 106,of the round contact bar 104 which is made of paramagnetic material, isattracted to both magnetic contacts 101 and 102 and will move intocontact with whichever of said contacts 101 and 102 it is closest to atany given time.

When the neck portion 106 touches the magnetic contact 101, or magneticcontact 102, it will remain in contact therewith until forced away by aplunger 107 or 108. In one closed position of the switch, the roundcontact bar 104 closes a circuit between contacts 102 and 103. When theplunger 107 is moved against the movable bar 104, the bar 104 pivotsabout the contact 103 and moves away from the contact 102, into themagnetic field of the contact 101 and immediately into snap contact withthe contact 101, thereby forming a closed circuit between contacts 101and 103 through the round contact bar 104.

To return the switch mechanism to the position wherein a closed circuitis effected between contacts 102 and 103 through the round contact bar104, pressure is applied by a plunger 108 which causes movable bar 104to pivot about a fulcrum 109 away from magnetic contact 101 into thefield of superior magnetic attraction of contact 102 and into snapcontact with the contact 102. The sequence of movements involvespressure by the plunger 108 against round contact bar 104, causing saidbar 104 to move away from contact 103 until said movement is stopped byperipheral contact of bar 104 with fulcrum 109. Continued pressure byplunger 108 then causes the movable bar 104 to pivot on the fulcrum 109whereby the neck portion 106 is moved away from the contact 101 into themagnetic field of the contact 102 and then into physical contact withthe contact 102. The plunger 100 is then released whereby the neckportion 105 of the bar 104 is snapped back into contact with the contact103 by the magnetidattraction of the contact 103.

The switch mechanism utilizing the three permanent magnets 101, 102 and103 may be operated with only the plunger 107. When a circuit is closedbetween the contacts 102 and 103 through the round bar 104, pressure onthe plunger 107 sufficient to break the contact between the contact 102and the neck portion 106 of the round bar 104 will bring the neckportion 106 into snap contact with the contact 101. Additional pressureon the plunger 107 will cause the bar 104 to pivot about the fulcrum109, thereby moving bar 104 away from the contact 101 and back into snapcontact with the contact 102.. Release of pressure on the plunger 107results in the return of the neck portion 10.5 01 the bar 104 intocontact with the contact 103.

The round movable bars 35 and 104 of this invention are of aparamagnetic material and preferably a ferrous alloy. The non-magneticelectrical contact 38 may be constructed of similar material. Contacts34, 40, 101, 102 and 103 are all constructed of permanent magneticmaterials. The surfaces of all these contacts, particularly thoseportions that ac'ually make electrical conta;t may be faced with silveror some other non-ferrous material which is particularly well suited forelectrical contacts. In such a case, the contacts may be considered asof composite construction.

The preferred embodiment and a number of modifications of the inventionhave been illustrated and described, but changes and other modificationscan be made and features of the invention can be used in differentcombinations without departing from the invention as defined in theclaims.

What is claimed is:

1. A self-cleaning magnetic switch including a round movable contact barmade of para-magnetic material held in electrical contact at one end bya magnetic contact that serves as a fulcrum for said round bar, andadjacent opposite sides of the other end of said round movable bar, amagnetic abutment and a second abutment, at least one of said abutmentsalso being an electric contact, whereby said round bar is positionedhaving one end in contact with said magnetic contact and the other endin contact with said magnetic abutment, and a plunger positioned on theside of said round bar which is adjacent said magnetic abutment at aposition intermediate the ends of said round bar whereby movement ofsaid plunger against said round bar thrusts said round bar away fromsaid magnetic abutment with a snap action and against said secondabutment.

2. A self-cleaning magnetic switch including a movable round contact barmade of para-magnetic material held in electric contact at one end by afirst magnetic contact that serves as a fulcrum for said round bar and asecond magnetic contact adjacent the other end of said movable barwhereby an electric circuit is formed between said two magnetic contactsand said round bar, and a plunger positioned on the side of said roundbar which is adjacent said second magnetic contact at a positionintermediate the ends of said round bar whereby movement of said plungeragainst said round bar thrusts said round bar away from said secondmagnetic contact with a snap action, and abutment means limiting themovement of said movable bar away from the magnet to a distance lessthan the effective range of the attraction of said magnetic contact.

3. A self-cleaning magnetic switch including a round movable contact barmade of para-magnetic material held in electric contact at one end by amagnetic contact that serves as a fulcrum for said round bar, and amagnetic abutment adjacent one side of the other end of said round bar,and an electric contact adjacent the side of said round bar oppositethat adjacent to said magnetic abutment, whereby said .round bar ispositioned having one end in contact with said magnetic contact and theother end in contact with said magnetic abutment, and a plungerpositioned on the side of said round bar which is adjacent said magneticabutment at a position intermediate the ends of said round bar wherebymovement of said plunger against said round bar thrusts said round baraway from said magnetic abutment with a snap action and into contactwith said electric contact whereby an electric circuit is formed betweensaid magnetic contact through said round bar which continues only solong as pressure is applied to said plunger.

4. A single pole, double throw self-cleaning switch including a roundcontact bar made of para-magnetic material held in electric contact atone end by a first magnetic contact that serves as a fulcrum for saidbar, and a pair of electric contacts adjacent opposite sides of theother end of said bar, one of said contacts being a nonmagnetic contactand the other of said contacts being a second magnetic contact whichattracts said bar whereby an electric circuit is formed between said twomagnetic contacts through said round bar, and a plunger positioned onthe side of said bar which is adjacent said second magnetic contact at alocation intermediate the ends of said bar, whereby movement of saidplunger against said round bar thrusts said round bar away from secondmagnetic contact with a snap action and into contact with saidnon-magnetic electric contact thereby forming a circuit between saidfirst magnetic contact and said nonmagnetic electric contact throughsaid round bar.

5. The switch of claim 4 characterized by having the plunger positionedagainst said round movable bar, guide means in which the plunger movesin a direction to thrust the round bar away from said second magneticcontact with a snap action and to impart a rotative movement to saidround bar, whereby the bar has a self-cleaning action.

6. The switch described in claim 4, characterized by a round contact barhaving a necked portion in contact with said first magnetic contact.

7. The switch described in claim 5, characterized by said first magneticcontact being a cylindrical bar having its axis substantially normal toa plane through the axis of said round contact bar.

8. The switch of claim 7 characterized by having the plunger positionedagainst said round movable bar, guide means in which the plunger movesin a direction to thrust the round bar away from said second magneticcontact with a snap action and to impart a rotative movement to saidround bar, whereby the bar has a self-cleaning action.

9. A self-cleaning switch having a housing in which the switch isenclosed in a chamber defined between an upper and a lower portion ofsaid housing, said switch having a first round magnetic contact barconnected to one side of said housing with its axis normal to the planeof said side, a round movable contact made of para-magnetic materialheld in electrical contact at one end by said first magnetic contact, anelectric contact connected to the same side of the housing as said firstmagnetic contact and substantially parallel to said first magneticcontact positioned toward the opposite end of said round movable bar,and a second magnetic contact positioned across said round bar from saidelectric contact, said second magnetic contact being connected to theside of the housing opposite to the side to which the first magneticcontact is connected and having its axis normal to the plane of the sideof the housing to which it is connected, said round movable bar beingnormally in contact with said first and second magnetic contacts wherebyan electric circuit is formed, and a plunger having one end positionedon the side of said round bar which is adjacent said second magneticcontact at a position intermediate the ends of said round bar, saidplunger having its other end extending outwardly through the. wall ofsaid housing, whereby movement of said plunger against said round barthrusts said round bar away from said second magnetic contact with asnap action and into contact with said electric contact thereby forminga circuit between said first magnetic contact and said electric contactthrough said round bar.

10. The switch of claim 9 characterized by having the plunger positionedagainst said round movable bar, guide means in which the plunger movesin a direction to thrust the round bar away from said second magneticcontact with a snap action and to impart -a rotative movement to saidround bar, whereby the bar has a self-cleaning action.

11. The switch described in claim 9 characterized by said electriccontact being positioned on the same side of said round bar as saidfirst magnetic contact.

12. The switch described in claim 11 characterized by a round contactbar having a necked portion in contact with said first magnetic contact.

13. The switch of claim 12 characterized by having the plungerpositioned against said round movable bar, guide means in which theplunger moves in a direction to thrust the round bar away from saidsecond magnetic contact with a snap action and to impart a rotativemovement to said round bar, whereby the bar has a self-cleaning action.

14. An electric switch including a round movable contact bar with endportions that constitute electric contacts of the circuit of the switch,two electric contacts above said round bar and each of which is adjacentto a different end portion of said round bar, each of said two electriccontacts being a magnet, another magnetic electric contact below theupper electric contact at one end of said round bar, two plungers atspaced locations along the length of said round bar and between the twoupper electric contacts, and a fulcrum under said round bar and nearerto the end of said round bar having the electric contacts both above andbelow said round bar, said fulcrum being at least as low as the lowerperiphery of said round bar when said round bar is incontact with thelower electric contact at the other end of said round bar, one of theplungers contacting with said round bar beyond the fulcrum on the sideof the fulcrum away from the end of said round bar that has electriccontacts both above and below it, and characterized by having theplunger positioned against said round bar, guide means in which theplunger moves in a direction to thrust the round bar away from thesecond magnetic contact with a snap action and to impart a rotativemovement to said round bar, whereby the bar has a self-cleaning action.

15. The switch described in claim 14 characterized by having the ends ofsaid round bar adjacent said electric contacts of reduced diameterthereby forming a neck to facilitate the pivotal contact between saidround bar and said electric contacts.

No references cited.

BERNARD A, GILHEANY, Primary Examiner.

1. A SELF-CLEANING MAGNETIC SWITCH INCLUDING A ROUND MOVABLE CONTACT BARMADE OF PARA-MAGNETIC MATERIAL HELD IN ELECTRICAL CONTACT AT ONE END BYA MAGNETIC CONTACT THAT SERVES AS A FULCRUM FOR SAID ROUND BAR, ANDADJACENT OPPOSITE SIDES OF THE OTHER END OF SAID ROUND MOVABLE BAR, AMAGNETIC ABUTMENT AND A SECOND ABUTMENT, AT LEAST ONE OF SAID ABUTMENTSALSO BEING AN ELECTRIC CONTACT, WHEREBY SAID ROUND BAR IS POSITIONEDHAVING ONE END IN CONTACT WITH SAID MAGNETIC CONTACT AND THE OTHER ENDIN CONTACT WITH SAID MAGNETIC ABUTMENT, AND A PLUNGER POSITIONED ON THESIDE OF SAID ROUND BAR WHICH IS ADJACENT SAID MAGNETIC ABUTMENT AT APOSITION INTERMEDIATE THE ENDS OF SAID ROUND BAR WHEREBY MOVEMENT OFSAID PLUNGER AGAINST SAID ROUND BAR THRUSTS SAID ROUND BAR AWAY FROMSAID MAGNETIC ABUTMENT WITH A SNAP ACTION AND AGAINST SAID SECONDABUTMENT.